Gustav pfannkuche



(No Model.)

G. PPANNKUGHE.

REGULATION 0E ALTERNATE CURRENT GENERATORS.

No. 398,448. Patented Nov. 27, 1888.

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UNITED STATES i l i ipn rfa# PATENT ich,

GUSTAV PFANNKUOHE, OE CLEVELAND, OHlO, ASSIGNOR TO THE BRUSH ELECTRIC COMPANY, OF SAME PLACE.

REGULATION OF ALTERNATEHCURRNT GENERTOES.,

SPECEEICATION forming part of Letters Patent No. 393,448, :lated November 27, 1888.

(No model.)

To all whom it may concern,.-

Be it known that l, GUsrAv PFANNK oor-rn, of Cleveland, in the county of Cuyahoga and State of Ohio, have invented certain new and useful Improvements in AlternatingOurrent Dynamos; andI do hereby declare the follow` ing to be a full, clear, and exact description ofthe invention, such as will enable others skilled in the art to which it appcrtains to r3 make and use the same.

My invention has reference to improvements in alternating-current dynamos, the object being to render such dynamos self-exciting and self-regulating, analogous in this respect to compound constant-potential continuous-current dy names, whereby the same become adapted for the operation of a system of distribution in which a constant dilierence of potential is required.

My improved dynamo is specially designed for use with such systems of distribution in which the translating devices are, in multiple arc branches, derived from a main or trunk line, and in which it is designed to maintain a constantdiiierence of potential at the terminals of the derived branches or working circuits, which are frequently at great distances from the generator. Insuehsystemsthedifterenceofpotential at the brushes of thepgenerator is dependent upon the relation of the external resistance to the total resistance in such manner that when the external resistance increases, the difference of potential at the brushes also in` creases, While at the same time less current is generated in the armature, and when the eX- ternal resistance decreases, the difference of potential at the brushes also decreases, and more current is at the same time generated in the armature. From this it becomes clear that in a multiple-arc system of distribution, Whenever one or more Working branches are opened, provision should be made to decrease the strength of the deldmagnets, and Whenever additional working-circuits are closed the strength of the field-magnets should be increased, in order to maintain a constant difference of potential. ln continuous-current dynamos this result is accomplished automatically by providing the field-magnets with two 5o Sets of coils, one set of which is in series with the armature-coils, and the other set in a shunt across the brush terminals of the dynamo, and the manner in which such dynamos operate to maintain a constant difference of potential under the varying resistance of the external circuit is so well understood 'oy those skilled in the art that a specific explanation is deemed unnecessary.

' In a dynamo set forth in aseparatc application for patent tiled by me l have applied the principles ofthe sel f-exciting compound dynamo to alternating -current generators, whereby the latter become adapted to the feeding of asystein of distribution in which a constant difference of potential is required. ln said separate application l have shown an alternatingcurrent dynamo in which two sets ol' fieldcoils, one

in series and the other in a de ived circuit, are charged by the alternating currents generated in the armature after the same have 7o been straightened out by suitable commutators, whereby separate exeiters are dispenser with; but in some cases, especially When the currents generated by the machine are of very high tension, which is frequently the casein alternatingcurrent generators, these currents are not Well adapted for charging the series coils of the field, and my present invention is designed to overcome this difficulty by reducing the tension ofthe currents designed to 8o charge one set of field-coils by a suitable inductiontransl'ormer the primary coil of which is in series with the armature, while the secondary is in circuit With the set of field-coils which it is designed to charge by the same. Thus S5 one set of field-coils is placed in a local circuit charged inductively by the currents traversing the line, which coils take the place ofthe series coils of the ordinary compound dynamo, While the other set is in a shunt substantially like the shunt-coils in an ordinary compound dynamo, but charged in the manner set forth in my aforesaid separate application. All this will more fully appear from the following detailed description, in which reference is made to the accompanying drawing, in which I have illustrated my invention mainly in diagram, omitting such details as are readily and necessarily implied.

The alternating-current generator l may be roo of any ordinary or improved construction. It is represented in the drawing as mounted upon a base or platform,2, upon which standards 3 3, of iron, are bolted,which constitute the yokes of the field-magnets. The armature 4, which is preferably of the Brush type, is mounted upon a shaft, 5, which may be journaled in the standards, and is driven in any suitableV manner. The alternating currents generated in this machine are collected by brushes 6 6, bearing upon collecting-disks 7 7, secured to but insulated from the shaft and having the terminalsofthearmature coilsconnected therewith. All these parts may be of ordinary construction well understood by those skilled in the art,and need not be specifically' described.

The collector-brushes 6 6 are connected with the main or trunk line 8 8, which is tapped at distant points by multiple-arc branches, as indicated at 9 9, Sie., in which suitable translating devices, 10 10, die., are placed. There are two se'ts of iield-coils,11 and 12, upon the fieldmagnets. 'lhe rst set is charged induetivel y by the full line-currents, and the other directly by currents diverted into a shunt, as will hereinafter more fully appear.

Upon a part of the armature-shaft which projects beyond the frame of the machine are mounted two commutators, 13 and 14, side by side, and each insulated from the shaft. Each of these commutators is composed of two hollow cylindrical blocks, 13 132 and 14 lig, respectively, each of which is provided at one end with a number of segmental teeth alternating with segmental spaces,'aud each pair of blocks is so mounted upon the armatureshaft that the teeth of one engage the corresponding spaces on the other, with insulating material (indicated by heavy lines) intervening between the two blocks.

There are two pairs of brushes for each commutator, one pair bearing upon the segmental portions and the other pair upon the continuous cylindrical portions thereof, and in the further description these brushes will be referred to as alternator-brushes 7 and straightenerbrushes,77 respectively.

The alternator-brushes 15 15 of commutator 14 are connected by wires 16 and 17, respectively, with the terminals of the secondary coil 18 of a transformer, 19, the primary coil 20 of which is in the main line 8 8, as shown. The alternator-brushes 21 2l of commutator 13 are connected, respectively, with wires 22 and 23, which form a shunt across the collector-brushes 6 6. The straightener-brushes 16 162 are connected, respectively, by wires 24 and 25 with the terminals of the set of field-coils 1l, while straightener-brushes 26 26 are connected, re-

spectively, by wires 27 and 28 with the terminals of the set of field-coils 12.

It must be understood that the total number of segments ofeach ofthe commutators is equal to the number of alternations of current in the generator and that they are so located upon shaft 5 relative to the coils of armature 4 that one of the alternator-brushes of each of these commutators will bear upon a segment of one of the blocks of which it is composed, while the other of these brushes will bear upon a segment of the other of the blocks during the prevalence of one electrical impulse.

The circuits can new be easily traced, and the operation will be readily understood. The alternating currents generated in the armature 4 will pass to the main line 8 8; but a portion of it is shunted by wires 22 23, which portion reaches commutator 13 by alternator-brushes 2l 21 and is straightened out by the operation of said commutator. Leaving tlie latter by one of the straightener-brushes 26 26', the new continuous current passes to and through the set of field-coils 12 and returns by the other of said brushes. The circuit, therefore,which includes the'field-coils 12 is strictly a local circuit, similar in this respect to the circuit which includes the shunt-coils of an ordinary compound dynamo, 'and it will presently be seen that the circuit which includes the set of coils 11 is also entirely a local circuit, different in this respect, essentially, from the circuit including the series coils of an ordinary compound dynamo. The line-currents pass through the primary coil 20 of transformer 19 and act inductively upon the secondary coil 18, generating in the latter alternating currents of comparative] y low tension, as is well understood by those skilled in the art. These currents reach commutator 14c by alternator-brushes 15 15', and after being straightened out by the operation of said coinmutator the new continuous current passes by one of the straightener-brushes 16 162 and wires 24 25 to and through the set of field-coils 11, which correspond to the series coils of the field-magnet of an ordinary compound dynamo. The regulating effect of this self-exciting alternating-current generator is substantially the same as that of an ordinary compound dynamo, although it is producedin a different manner. Suppose the machine is running at such rate as to charge the line, which is tapped by a given number of multiple-arc `working branches, with the required quantity of current and to produce the required difference of potential. If, now, a number of working-circuits are opened, both the external resistance and the total resistance is increased 5 but the relation of the external to the total resistance is so changed as to produce an increased difference of potential, while less current is generated in the armature. By reason of the fall of current upon the line less eurrent traverses the primary coil 20 of transformer 19, less current is generated in the secondary coil 18 of said transformer, and the magnetizing effect of the set of field-coils 11 is reduced 5 but by reason of the increased difference of potential more current than before is diverted into the shunt 22 23, which includes the set of field-coils 12, and the magnetizing effect of these coils is increased. The aggregate effcct of the two sets of field-coils, however, is diminished, the field weakened, and the difference of potential is consequently reduced, thus re-establishing the original difference of potential. If, on the other hand, additional working-circuits are closed whereby both the external and total resistance are reduced, and the relation of these resistances so changed as to produce a decrease of difference of potential, while at the same time more current is generated. By reason of the increase of current upon the line more current traverses the primary coil 2O of transformer 19, more current is generated in the secondary coil 1S of said transformer, and the magnetizing effect of the set of coils 11 is increased; but by reason of the fall of difference of potential less current than before is diverted into the shunt 22 23, which includes the set of field-coils 12, and the magnetizing effect of these coils is reduced. The aggregate effect of the two sets of field-coils, however, is increased, the field strengthened, and the difference of potential is consequently raised, thus re-establishing the original difference of potential. Thus it will be seen that any change inthe system that tends to vary the difference of potential will react upon the dynamo to cause the same to re establish the original difference of potential. The currents generated in this dynamo will ordinarily be of very high tension, which currents can be sent to great distances over comparatively thin conductors. Such currents, however, are not well adapted for the operation of the more common translating devices-like motors, lamps, dse-and before reaching such translating devices the original currents should be transformed into currents of lower tension. This may be done by any suitable transformer, and in the drawing I have shown inductiontransformers 10 10, &c., with their primary coils in the multiple-arc branches 9 9 and their secondary coils in the workingcircuits proper. It will, however, be understood that I am not limited to this arrangement, since other suitable translating devices adapted to be operated by hightension currents may be substituted for theinduction-,transformers shown.

Other changes may be made in the general arrangement of the parts without departing from the fundamental idea of my invention. Thus I can charge the set of eld coils 12 inductively the same as field-coils 11. This is indicated in dotted lines. In that case I use an additional transformer, 30, the fine-wire primary coil 3l of which is in ashunt from the line with which it is connected by wires 33 and St. The coarse-wire secondary coil of this transformer is then connected by wires 35 and 36 with the alternator-brushes 21 and 21', respectively, while the shunt-wires-22 and 23 Field-coils 12 are thus charged are omitted.

with straightened low-tension currents, which enable me to use coarse wires for these coils, and which reduce the sparking at the commutator 13.

Having now fully described my invention, I claim and desire to secure ny Letters Patent- 1. In a self-exciting alternatingcurrent dynamo, the combination, with a generating-armature and field-magnets provided with two sets of eld coils, of an induetorium and a commutator for straightening the secondary currents of the inductorium, and conductors for transmitting such straightened current to one set of held-coils, and a commutator for straightening a portion of the current in the main line, and conductors for transmitting such straightened current to the other set of field-coils, substantially as set forth.

2. In a self-exciting alternatiiig-current dynamo, the combination, with a generating-armature and field-magnets, thelatter provided with two sets of field-coils, of an inductoriuni included in the main line, and a commutator for straightening the secondary currents, and conductor for transmitting such straightened current to one set of held-coils, and a commutator included in a shunt from the main line, and conductors for transmitting the straightened current from said shunt tothe other set of field-coils, substantially as set forth.

3. In a self-exciting alternating-current dynamo, the combination, with a generating-armature and collectors for taking the alternating electrical impulses from the saine, of field-magnets having one set of coils in circuit with the secondary coil of a transformer, the primary of which is in the main line, a second set of field-coils in a shunt across the collectors, and a commutator for each set of fieldcoils for straightening the currents through the same, substantially as described.

4. In a self-exciting alternatingcurrent dynamo,the combination, with held-magnets having two sets offield coils, ofan inductorium constructed to transform the current from the main lineinto secondarycurrentsofrednced tension, and a commutator for straightening the secondary currents to one set of field-coils, and a commutator in a shunt from the main line for straightening the current in the shunt to the other set of tieldcoils, substantially as set forth.

In testimony whereof I have signed this specification in thepresence of two subscribing witnesses.

GUSTAV PFANNKUCHE.

Witnesses:

ALBERT E. LYNCH, DANL. KnsrnR.

ICO 

